Tooth and adaptor for dredging machine

ABSTRACT

The tooth and adaptor for dredging machines object of the present invention relates to a tooth or wear member which, attached to an adaptor or adaptor member, creates an assembly the purpose of which is to deepen and clean the beds of ports, rivers, channels, etc., removing therefrom sludge, stones, sand, etc., the adaptors being attached to the blades of the propellers and thus forming the cutter head of the dredging machine. The constructive features of the coupling between the tooth and the tooth bar or adaptor allow making better use of the cutting material of the tooth and a simple and quick replacement thereof in the adaptor, between other advantages.

OBJECT OF THE INVENTION

The present invention, tooth and adaptor for dredging machines, relatesto a tooth or wear member which, attached to an adaptor or adaptormember, creates an assembly the purpose of which is to deepen and cleanthe beds of ports, rivers, channels, etc., removing therefrom sludge,stones, sand, etc., the adaptors being attached to the blades of thepropellers and thus forming the cutter head of the dredging machine.

The dredging machine, or dredger, allows excavating, transporting anddepositing material that is located under the water, and they can bemechanical or hydraulic machines, the mechanical machines being usedwith cutting members, teeth or blades for their use on compact terrain.

The tooth and adaptor object of the present invention are preferablyintended to be used in dredging machines having a suctioning cutter headof the type which while at the same time it excavates the terrain underthe water, the loosened material is suctioned by a pump and transportedthrough a pipe to somewhere else.

STATE OF THE ART

Systems of tooth and adaptor or adaptors are known in the state of theart for their application in dredging operations. The main objective ofsaid operations is to remove material from marine or river beds, and todo this it is common to use dredge boats including a dredge or dredgingmachine on which the various teeth are arranged and in turn connected totooth bars or adaptors.

The U.S. Pat. No. 3,349,548-B describes a tooth and adaptor systemattached to one another by means of an elastic strap such that if suchstrap is poorly arranged, the entire system is altered as to its correctassembly. It also only has one contact area between the tooth and theadaptor, which negatively affects the distribution of stresses.

Another, also US, U.S. Pat. No. 4,642,920-B describes a tooth andadaptor system attached to one another by means of a retaining systemformed by a pin, the area where the pin is housed being easily accessedby dirt, making the subsequent removal thereof difficult. This systempresents difficulty in absorbing the torsional and bending stresses andloads, generating a strong lever reaction in the system. As with thepreceding patent document, there are few contact surfaces between thetooth and the adaptor.

Spanish patent document number ES-2077412-A describes a tooth andadaptor assembly made up of three parts requiring the use of twofastening systems. The fact that it has three parts complicates theentire system because it requires a larger number of spare parts andthree fastening systems, one of which requires the use of a hammerwhereas the other two fastening systems are formed by welding, makingthe tasks for replacing them long and complex.

The solutions existing in the state of the art for dredging machineshave, among others, the following drawbacks:

-   -   The teeth are solid members such that the material of said        members is not optimized for the functions for which it has been        designed. Another drawback of using the solid teeth known in the        state of the art is that they are more difficult to handle due        to their weight.    -   The teeth used in the state of the art for the same application        are larger, requiring more space for storage thereof.    -   The interlockings between tooth and adaptor known in the state        of the art have a retaining member or vertical pin assuring the        attachment between said tooth and the adaptor during operation        thereof. When the tooth becomes worn it is necessary to replace        it and to that end the cutter head is taken out of the water and        usually has material from the aquatic bed where it is working        adhered to the lower part of the teeth and adaptors. Said pin is        usually removed by striking said pin at the upper part and re        moving it through the lower part of the tooth-adaptor assembly,        which often causes the pin to fall into the water (since the        tooth is changed above the water) preventing recovery thereof.        Likewise, the fact that there is material adhered to the lower        part of the tooth-adaptor assembly makes it difficult to remove        the mentioned pin because it prevents the pin from coming out of        its housing. Furthermore it is common for the pin to be lost        when it is inserted in the mass of material adhered to the        assembly and subsequently falling into the water.    -   Due to the configuration of the interlockings existing in the        state of the art, the teeth are excessively large, generating        long interlockings, with less strength in the tooth, a larger        occupied volume and an increase of the distance from the cutter        head to the blade, which reduces the performance of the tooth        and the assembly.    -   The adaptor likewise has no additional protection other than the        protection provided by the tooth and is affected by the        materials loosened due to the action of the tooth and striking        against the adaptor, causing damage and wear thereof.

DESCRIPTION OF THE INVENTION

The invention describes a tooth with a front wear part and a rearprojecting part or nose intended for being housed within a hollowingarranged in the body of an adaptor and an assembly formed by both fordredging machines, both members being attached to one another by meansof a preferably hammerless, preferably vertical-type, retaining system,i.e. without needing to use hammers or without having to strike the pinattaching both members to one another. The adaptor is attached to theblade of the cutter head of the dredging machine at the end opposite tothe hollowing by means of a coupling adapted for such purpose.

The object of the present invention is a tooth, an adaptor and theassembly formed by both, preferably applied to dredging machinery,allowing optimal wear of the material of the tip of the tooth andcoupling between the tooth and the adaptor. These objects of theinvention are achieved due to a particular construction of the contactsurfaces between both members, allowing the self-tightening force to beproduced close to the force (load), such that the horizontal componentof the rearward reaction is larger and therefore the self-tighteningforce is also larger since the tooth pushes against the adaptor.

In dredging operations the tooth must be replaced on the actual dredgeboat, i.e. at the worksite or the operations area, usually on the waterand working directly on the cutter head carrying the adaptors, or toothbar, and the teeth. Said operations are carried out by the employees onsaid boat, i.e. at the work site, far from maintenance shops with thesuitable conveniences and tools for optimally performing these types ofoperations. For this reason all the mentioned components can be coupledwith fastening members and pins so that the replacement operations aresimple, without an excessive number of tools and preventing the use ofcomplex equipment.

Another object of the present invention is to present in addition to thetooth-adaptor assembly, a tooth as well as an adaptor which, due totheir configuration, allow a distribution of stresses that favorsretaining the tooth in the adaptor and reducing the stresses to whichthe retaining system, and specifically the pin thereof, is subjected.The configuration of the tooth and of the adaptor can also be usedoutside of dredging operations, such that the adaptor or tooth bar canbe connected to the bucket of an excavating machine or the like foron-shore works.

The tooth and adaptor object of the present invention have contactsurfaces and constructive features allowing the coupling between bothmembers to increase the performance of the coupling, particularly theefficiency of each tooth, thus improving the efficiency of the dredgingmachine.

The tooth is made up of two different parts, a first wear part, which isthe part acting on the terrain and is subject to erosion due to theterrain, and a second part or nose, which is the part that is insertedin a housing arranged for such purpose in the adaptor, forming theinterlocking of the system, and subjected to the reactions and stressesgenerated by the work of the tooth on the terrain. Said nose is formedby a lower base body and an appendage integrated in the upper surface ofsaid lower base body, one of its ends being free and at the opposite endsaid nose is attached to the wear part. The gap between the wear partand the nose is determined by the upper surfaces of the appendage and bythe lower surface of the lower base body which, after reaching a maximumheight from the free end of the nose, converge towards the tip of thetooth, such that the union line of both surfaces is located on the sideof the wear part of the tooth and in front of the line of maximum heightof the nose.

The longitudinal vertical section of the nose varies along the lengththereof, and has at the free end thereof a cross-section with roundedvertices. The area of the cross-section of the nose gradually increasesas the nose approaches the end for being attached to the wear part ofthe tooth, specifically until a maximum height is reached between thelower side of the base body and the upper side of the appendage of thebase body. After this point the area of the cross-section of the nosebegins to decrease until the upper surface of the appendage intersectswith the lower surface of the base body.

Said section can have different shapes, such as elliptical, trapezoidalor rectangular shapes, but having at least four sides.

The appendage located in the upper part of the nose, and the trapezoidalcross-section of which is narrower than the section of the base of thenose, is centered with respect to the latter. The height of saidappendage is preferably nil in an area close to the free end of the nose(although it is possible for the appendage to have a certain height atsaid free end) and such height gradually increases until reaching saidpoint of maximum height before decreasing again. The lateral sides ofthe successive cross-sections of the appendage and the upper side of thesuccessive cross-sections of the base body of the nose of the tooth forman angle varying, due to manufacturing issues, between 45° and an angleof less than 180°, preferably between 45° and 135°. Even more preferablythe angle is greater than 90°, such that the lower base of the appendageis larger than the upper base, although the opposite is also possible,i.e. the angle is less than 90°

The nose likewise has at least one first contact area with the innersurface of the housing of the adaptor, such contact area being formed bythe two upper surfaces of the base of the nose that are located on bothsides of the appendage of the nose of the tooth. The main feature ofthis first contact area is that it achieves the self-tightening of thetooth in the adaptor.

Due to the proximity of these surfaces with the tip of the tooth, i.e.the point of application of the force produced during the work of thetooth on the terrain, causes the reactions on said surfaces to begreater and therefore the self-tightening forces (components of saidreactions} are also greater.

The nose has a second contact area with the adaptor, this contact areabeing located on the lower surface of the base of the nose, in the areaclose to the free end thereof.

The adaptor is also made up of two parts: at one end it has aconfiguration that can vary depending on the type of machinery to whichit is connected, i.e. either a cutter head of a dredging machine, or tothe bucket of an excavating machine, whereas at the opposite end it hasa hollowing, housing or cavity intended to receive the nose of thetooth. The inner configuration of the surfaces of the hollowing orhousing of the adaptor for receiving the tooth are complementary to thatof the nose of the tooth, thus assuring a perfect coupling between bothmembers.

For the coupling between the tooth and the adaptor, both partspreferably have a hole or through borehole from the upper part of theadaptor, traversing the nose of the tooth, and to the lower part of theadaptor. A pin preferably with surfaces of revolution and with apreferably hammerless retaining system (which does not require strikingwith a hammer or mallet for being inserted or removed) aiding inchanging teeth in the adaptor will be inserted in said housing.

The coupling of the rear part or nose of the tooth in the hollowing orhousing of the adaptor is due to the conjunction of the planes definingthe described locking surfaces. A tightening or crushing effect betweenthe tooth and the adaptor is furthermore achieved by means of saidplanes when a stress is applied perpendicular to the wear tip of thetooth and upwardly, this being the normal working situation of the teethin a cutter head of a dredging machine.

Due to this interlocking system, the pin is subjected to fewer stressesthan in conventional interlocking systems since the to oth-adaptorsystem tightens itself when it is subjected to upward vertical loads inthe tip of the tooth, releasing stresses into the retaining system andits pin, and therefore allowing designing pins of the retaining systemwith a smaller size and section since they are subjected to fewerstresses, thus reducing deterioration or mattage of the pin and allowingit to be reused.

With the described configuration of the coupling the contact surfacesbetween the tooth and the adaptor are closer to the working tip of thetooth than in known couplings. This reduces the lever effect createdbetween the tooth and the adaptor, and therefore the stresses to whichthe assembly is subjected, including the fastening or retaining system,are also reduced, thus reducing deterioration or mattage. Reducing leverstresses in the tooth allows reducing the dimensions of the nose of saidtooth. And furthermore, due to its geometry, the resistant section ofthe rear projection or nose decreases towards the free end thereof, suchthat the bending moments in said area, caused by the load at the tip ofthe tooth, decrease and therefore the larger moments are located at thepoint where the resistant section is larger. Reducing the totaldimensions of the system also allows therefore reducing the height ofthe interlocking, thus achieving a more deeply penetrating system.

The tooth object of the invention together with the adaptor allowsoptimizing the wear material, i.e. the use of the material arranged inthe front wear part of the tooth, which is the part that directly actson the terrain, is optimized. Said optimization is achieved by reducingthe material of the tip of the tooth that is not going to be used to aminimum. The material forming part of the tip of the tooth, or wear tip,and which is then not worn, is material that has been paid for but thennot used for its purpose. The material of the tip of the tooth isoptimized because the tip has been designed according to the inclinationof the upper surface of the appendage of the nose, which is parallel tothe line of wear of the tooth, thus making use of the largest possibleamount of material at the tip of the tooth before being replaced with anew tooth.

Due to this configuration of the tooth-adaptor coupling, and taking intoaccount that dredging operations are done “blindly” for the user, thetip of the tooth must be completely worn, the unused wear material beingminimal, before the tooth bar begins to become worn, since if thisoccurs it causes a serious drawback both in terms of time and financialresources, since not only the tooth but also the adaptor has to bereplaced. It is necessary to take into account that the wear time of theteeth further depends on the revolutions at which the cutter head works,of the material it is working on, it being difficult to predict the lifeof the teeth. It also so happens that once the tooth is worn, and beforethe tooth bar begins to be worn due to the direction action on theterrain, the user perceives increased vibrations, notifying him or herthat the tip of the tooth has already been consumed. Said vibration isdue to the fact that as the tooth gradually wears, the section thereofgradually increases, the section of attack of the tooth on the terraintherefore being increasingly larger, causing the mentioned vibrationsince the optimal section for penetration has been consumed, such thatwhen the entire section of the tip of attack has been consumed and thetooth bar is reached, said vibration is very large notifying theoperators that it is necessary to replace the tooth.

Another object of the invention consist of the tooth being able to havebetween the front wear part and the nose for coupling to the adaptor,according to the previously defined inclined planes, a perimetralprojection or flange or collar, the main purpose of which is to protectthe contact area between the tooth and the adaptor from the materialloosened during its dredging operation. Said collar also carries outthree functions in the coupling:

-   -   Protecting the adaptor from wear through the deflectors in the        upper and lower areas and which have been designed to redirect        the flow of loosened material, preventing such material from        rubbing or striking against the adaptor and therefore preventing        the wear thereof,    -   Preventing the loosened material from entering into the        interlocking, acting as a plug and also reducing the entrance of        material in the fastening or retaining system, and    -   Making contact with the adaptor after prolonged wear through        stoppers located in the upper and lower areas, said stoppers        being thicker to resist the larger stresses to which it is        subjected when contact with the adaptor is made, determining a        third contact area between the tooth and the adaptor.

Said collar can have variable thicknesses along its length depending onthe stresses to which it is subjected during the work of the coupling.Specifically, said collar has the thickest areas in its upper and lowerarea such that when contact is made, the reactions of the tooth bar onthe collar exert a component directly opposing the applied force (Fc).In addition the middle area of the collar has a curve towards the tip ofthe tooth that adapts to the shape of the interlocking, according to theparallelism to planes S and I and allowing the contact areas to becloser to the tip of the tooth, this area being where the main contactareas, located close to said tip to also reduce the lever effect, arelocated. Said central areas have less thickness than in the upper andlower areas.

Another object of the invention is a tooth the nose of which is hollow,such that the amount of material that is worn out is reduced.

DETAILED DESCRIPTION OF THE DRAWINGS

To complement the description being made and for the purpose of aidingto better understand the features of the invention, according to apreferred practical embodiment thereof, a set of drawings is attached asan integral part of said description which show the following with anillustrative and non-limiting character:

FIG. 1 depicts a perspective view of a collarless tooth and an adaptorprior to their coupling.

FIG. 2 depicts a side elevational view of a collarless tooth and anadaptor prior to their coupling.

FIG. 3 depicts a perspective view of a collarless tooth.

FIG. 4 depicts the rear elevational view of a collarless tooth.

FIG. 5 depicts a side elevational view of a collarless tooth.

FIG. 6 depicts a plan view of a collarless tooth.

FIG. 7 depicts a side elevational view of a collarless tooth showing theinclined planes S and I.

FIG. 8 depicts a side elevational view of a tooth with a collar.

FIG. 9 depicts a front elevational view of a tooth with a collar.

FIG. 10 depicts a plan view of a tooth with a collar.

FIG. 11 depicts a cross-section of a solid tooth with a collar.

FIG. 12 depicts a cross-sectional view of a hollow collarless tooth.

FIG. 13 depicts a side elevational view of a collarless tooth.

FIG. 14 depicts a section, according to Y-Y, of the hollow collarlesstooth of FIG. 13.

FIG. 15 depicts a section, according to Z-Z, of the hollow collarlesstooth of FIG. 13.

FIG. 16 depicts a section, according to AC-AC, of the hollow collarlesstooth of FIG. 13.

FIG. 17 depicts a section, according to AA-AA, of the hollow collarlesstooth of FIG. 13.

FIG. 18 depicts a section, according to AB-AB, of the hollow collarlesstooth of FIG. 13.

FIG. 19 depicts a section, according to AE-AE, of the hollow collarlesstooth of FIG. 13.

FIG. 20 depicts a perspective view of an adaptor.

FIG. 21 depicts a view of an adaptor.

FIG. 22 depicts a rear view of an adaptor.

FIG. 23 depicts a section, according to AB-AB, of the adaptor of FIG.22, showing the inclined planes SA and IA.

FIG. 24 depicts a view of a collarless tooth and an adaptor coupledtogether.

FIG. 25 depicts a section, according to AE-AE, of the coupling between acollarless solid tooth and an adaptor shown in the FIG. 24.

FIG. 26 depicts a collarless tooth and an adaptor coupled togethershowing the forces to which the assembly may be subjected and itsreactions.

FIG. 27 depicts a collarless tooth in which the appendage of the nose ofsaid tooth has a certain height along its entire length.

DESCRIPTION OF A PREFERRED EMBODIMENT

As observed in FIG. 1, the invention object of the present application,tooth and adaptor for dredging, is formed by an interchangeable tooth10, an adaptor 20 coupled to a blade of a cutter head of a dredgingmachine, and a retaining member 30 responsible for assuring theconnection between the tooth and the adaptor.

As can be observed in FIG. 3 and FIG. 20, the tooth 10 consists of afront wear part 11 or tip of the tooth responsible for the task oferoding the terrain, in contact with the ground and stones, and in itsrear part it has a projection or nose 12 intended for being housed in ahousing or hollowing 24 arranged in the adaptor 20.

FIG. 4 shows how the nose 12 of the tooth is formed by a lower base body16 and an appendage 15 integrated in its upper surface, with a free end14 attached at the end opposite to the front wear part, said nose 12being separated from the wear part by the intersection of the uppersurfaces of the appendage and the lower surface of the base body. Morespecifically, the gap between the wear part 11 and the nose 12 isdetermined by the two inclined planes S, I determined by said uppersurfaces of the appendage and lower surface of the base body, such thatthe imaginary horizontal intersection line of both planes 1 ₁ is locatedin front of the vertical line (h_(max1)-h_(max2)) determining themaximum height of the tooth 10, located in the side opposite to that ofthe free end of the nose 14. Said maximum height of the tooth H3 isformed by the maximum height of the base body H1 combined with themaximum height of the appendage H2.

According to a first vertical plane XY varying along the horizontal axisx, the base body of the nose, FIG. 13 to FIG. 19, has a cross-section atthe free end x₀, according to a second vertical plane YZ, with arectangular shape with rounded vertices such that the area of thecross-section, along the horizontal axis x, of the nose 12 graduallyincreases as the nose approaches the end for being attached to the wearpart of the tooth, inclined planes S, I, specifically until the lowersurface of the nose intersects the lower inclined plane I, after thepoint where the area of the cross-section along the horizontal axis x ofthe nose begins to decrease again until the intersection x₁ of theinclined upper S and lower I planes.

In addition, the section of the appendage 15 of the nose 12 of the tooth10 has a trapezoidal cross-section, its lower base being narrower thanthe upper surface of the base body of the nose 16 and centered withrespect to said base body 16, such that the height of said appendage isnil in an area close to the free end 14 of the nose x₀, and its heightgradually increases until reaching a maximum height H2, at which pointthe upper surface of said appendage 15 and therefore of the nose 12intersects the upper inclined plane S of separation with the wear partof the tooth 11, the height of the appendage decreasing after this pointuntil reaching the intersection x₁ of the upper S and lower I inclinedplanes. Said appendage 15 could also not have nil height at the free endof the nose 14 (see FIG. 27), or not be centered with respect to thebase of the nose 16.

The lateral sides 151, 152 of the successive cross-sections of theappendage 15 and the upper side 121, 122 of the successivecross-sections of the base of the nose 16 of the tooth 10 form an anglevarying between 45° and 180°, preferably between 45° and 135°, and evenmore preferably greater than 90°.

According to the foregoing, the description provides that the nose ofthe tooth 10 has a lower base body 16, with a section of at least foursides (a, b, c, d) with rounded vertices and with an upper surface 120and a lower surface 123. On said lower base body 16 there is an upperappendage 15 with an upper surface 153 and a lower surface 154, and witha trapezoidal section the lower base 154 of which is larger than theupper base 153 and the lower base 154 is in turn narrower than the uppersurface 120 of the lower base body 16 and is centered with respect tothe upper surface 120 of the lower base body 16. The nose also has afree end 14, opposite to the front wear part or tip 11, and an endopposite to the mentioned free end and attached to the tip 11 of thetooth 10.

The nose of the tooth and its section, as well as that of the area ofattachment with the front part of the tooth or tip of the tooth, isdetermined by the progressive gap of the upper 120 and lower 123surfaces of the lower base body 16 starting from a point close to thefree end 14 of the nose 12 and therefore increasing the section of saidbase body 16 in the direction of the tip of the tooth 11, until defininga maximum gap H1 corresponding with the maximum height H1) of the lowerbase body 16. The upper 153 and lower 154 surfaces of the appendage 15also progressively separate from one another from a point close to thefree end 14 of the nose 12, thus increasing the section of saidappendage 15 in the direction of the tip of the tooth 11, untildetermining a maximum gap H2 defining the maximum height H2 of theappendage 15. The union of the maximum heights H1, H2 of the lower basebody 16 and of the appendage 15, determine a line of maximum height H3of the nose of the tooth 12, such that after said line of maximum heightH3 the upper surface 153 of the appendage 15 and the lower surface 123of the lower base body 16 begin to converge towards the tip 11 of thetooth 10 until the union of both surfaces 153, 123, the union line ofboth surfaces 11 being located on the side of the wear part of the tooth11 and in front of the line of maximum height H3. Said maximum height islocated at a balance point between good penetration of the system, whichas mentioned depends on the total height of the nose, and of theresistance of the system, which depends on the stresses to which it issubjected.

The adaptor, FIG. 20, is formed by a body having a coupling 21 at oneend to be attached to a blade of the cutter head of a dredging machineand at the opposite end it has a hollowing or housing 24 for receivingthe rear projecting part or nose 12 of a tooth 10, which is inserted insaid housing 24. The inner surfaces, FIG. 22, of said housing 24 of theadaptor 20 are complementary to the surfaces of the nose 12 of the tooth10. In other words, said housing 24 is formed by a lower base hollow 22and an inverted T-shaped appendage in its upper surface 25 in theopening 28 of the housing 24 coinciding with the free end thereof. Theshape of said free end or opening 28 is defined by two inclined planes,an upper plane SA and another lower plane IA, which correspond with theupper surface of the hollow appendage and with the lower surface of thebase hollow of the nose, intersecting at their intersection line (orpoint) 12 formed by the infinite points x₃ of the intersection of theplanes, such that the intersection line 1 ₂ of both planes is in frontof the line (h_(max1)-h_(max2)) determining the maximum height A3 of thehollowing 24, as shown in FIG. 23.

As previously described, the inner surfaces are complementary to that ofthe nose of the tooth, therefore the infinite sections of said housingare complementary to the infinite sections of the nose of the tooth suchthat according to a first vertical plane XY, which varies along thehorizontal axis x, the hollowing has at the bottom 26 of the hollowing24, opposite to the opening 28, a cross-section, according to a secondvertical plane YZ, with rectangular shape with rounded vertices, suchthat the area of the cross-section of the hollowing 24 graduallyincreases as it approaches the opening 28 of the hollowing 24 (planesSA, IA), specifically until the lower side of the hollowing 24intersects with the lower inclined plane IA, such that after this pointthe area of the cross-section of the hollowing 24 begins to decreaseagain until the intersection x₃ of the inclined upper SA and lower IAplanes.

Likewise the section of the upper appendage 25 of the hollowing 24 has atrapezoidal cross-section, narrower than the base of the hollowing 22,and centered with respect to same 22, such that the height of saidappendage is nil in an area close to the bottom of the hollowing 26, andits height gradually increases until the upper surface of said appendage25 intersects with the upper inclined plane SA of separation, the heightof the appendage 25 decreasing after this point until reaching theintersection x₃ of the inclined upper SA and lower IA planes. Likewise,the upper appendage 25 may not end in its area close to the bottom ofthe hollowing 26 with nil height, but rather with certain height, and itcould also not be centered with respect to the base of the hollowing 22.

Obviously as in the nose 12 of the tooth 10, the lateral sides 251, 252of the successive cross-sections of the appendage 25 and the upper side221, 222 of the successive cross-sections of the base of the hollowing22 forms an angle with one another varying between 45° and 180°,preferably between 45° and 135°. Even more preferably said angle isgreater than 90°.

In other words, the adaptor 20 has at the end opposite to that of thecoupling 21 a hollowing or housing 24 for receiving the rear projectingpart or nose 12 of a tooth 10, which is completely inserted in saidhousing 24. Said housing 24 is formed by a lower base hollow orhollowing 22 having a section of at least four sides with roundedvertices, an upper surface 220 and a lower surface 223, arranging onsaid upper surface a hollow upper appendage 25 forming the housing 24 ofthe nose 12 of the tooth 10. Said hollow appendage 25 is formed by anupper surface 253 and a lower surface 254, and it also has a trapezoidalsection the lower base 254 of which is larger than the upper base 253and such lower base 254 is in turn narrower than the upper surface 220of the lower base hollow 22, said hollow appendage 25 being centeredwith respect to the upper surface 220 of the lower base body 22. Thehousing 24 has an opening 28 at the end opposite to the end for couplingthe adaptor to the, and an end opposite to that of the opening 28forming the bottom 26 of the housing 24, and therefore located close tothe coupling to the blade. The housing 24 of the adaptor 20 is alsodetermined by the upper 220 and lower 223 surfaces of the lower basehollowing 22 which progressively separate from one another from a pointclose to the bottom of the hollowing 26 of the adaptor 20, such that thesection of said base hollowing 22 gradually increases in the directionof the opening 28 of the adaptor 20 until a maximum gap A1 is defined,corresponding with the maximum height A1 of the lower base hollowing 22.The upper 253 and lower 254 surfaces of the hollow upper appendage 25progressively separate from one another from a point close to the bottomof the hollowing 26 of the adaptor 20, the section of said hollowappendage 25 thus increasing in the direction of the opening 28 of theadaptor 20, until determining a maximum gap A2 defining the maximumheight A2 of the hollow appendage 25. The union of both heights A1, A2of the lower base hollowing 22 and of the hollow appendage 25 determinea line of maximum height A3 of the opening 24 of the housing 24 of theadaptor 20. After said line of maximum height A3 the upper surface 253of the hollow appendage 25 and the lower surface 223 of the lower basehollowing 22 begin to converge in the direction opposite to that of thebottom of the hollowing 26 until the union of both surfaces 253, 223,the union line of both surfaces 12 being located on the opposite side ofthe bottom of the hollowing 26 and in front of the line of maximumheight A3 of the opening 28 of the hollowing 24 of the adaptor 20.

As shown in FIG. 24 and FIG. 25, both members are coupled together byinserting the nose 12 of the tooth 10 into the housing 24 of the adaptor20, the different complementary surfaces of the nose 12 and of thehousing 24 coming into contact with one another.

At the same time the adaptor 20 has been installed through its coupling21 in the blade or propeller of the cutter head of the dredging machine,the tooth 10 is installed, using for that purpose a preferablyhammerless retaining member 30, i.e. a member that does not require theaction of a mallet or hammer for removing it from or inserting it in thehousings intended for such purpose in the tooth and in the adaptor. Theretaining system is vertical, being inserted and removed through theupper part of the tooth and of the adaptor, traversing the nose 12 ofthe tooth 10 and the body of the adaptor 20 through respective throughholes 13, 23.

Once the assembly is put together and during the working operations, thetooth 10 is subjected at its tip 11 to an upward perpendicular force(Fc) in the lower side of the tip of the tooth 11, less commonly beingable to be subjected to a force normal Fs to the tip of the tooth due tothe swell of the boat, causing a series of stresses and reactions in thecoupling between the tooth 10 and the adaptor, specifically in thecontact surfaces between both.

The first contact area between both is formed by the two surfaces, bothin the tooth and the adaptor, coming into contact with one another,specifically those which are located on both sides of the appendage 15of the nose 12 of the tooth 10 or of the appendage 25 of the hollowing24 of the adaptor 20, i.e. surfaces 121, 122 in the tooth 10 andsurfaces 221, 222 in the adaptor 20. This first contact area, which isvery close to the tip of the tooth 11, generates self-tighteningreaction Rx2 preventing the tooth 10 from being ejected from the adaptor20 due to the stresses to which it is subjected. It is also possiblethat there is only one first contact surface between the tooth 10 andthe adaptor 20, for example in the case in which the appendage 15 of thenose 12 of the tooth 10 is not centered with respect to the base of thenose 16 of the tooth 10.

A constructive alternative in the tooth 10 consists of arranging acollar or flange 40 therein (see FIG. 8 to FIG. 11), located on theperimeter of the tooth and coinciding with the gap previously definedbetween the front part of the tooth or tip 11 thereof and the beginningof the nose 12 of the tooth 10. The thickness or width of said collar 40varies depending on the area of the tooth it surrounds depending on thestresses to which said area is subjected.

Another feature of the tooth 10 object of the present invention is thatthe nose 12 of the tooth 10 has a hollowing or cavity 50 to reduce theweight of the tooth without affecting its mechanical features (see FIG.12).

It should be mentioned that the adaptor has at least one groove 27 inits contact area with the tooth for inserting a tool and aiding inremoving the tooth once the retaining member arranged between both hasbeen removed.

1. A tooth for being connected to an adaptor by a retaining system, saidtooth having a front wear part or tip intended for being in contact withdirt and stones, and a rear coupling part, said rear coupling part is aprojection or nose comprising: a lower base body, with a section of atleast four sides with rounded vertices and with an upper surface and alower surface, an upper appendage arranged on the lower base body, withan upper surface and a lower surface forming an upper base and lowerbase of a trapezoidal section, respectively, the lower base beingnarrower than the upper surface of the lower base body and beingcentered with respect to the upper surface of the lower base body, afree end opposite to the front wear part or tip, and an end opposite tothe free end and attached to the tip of the tooth, wherein the upper andlower surfaces of the lower base body progressively separate from oneanother from a point close to or at the free end of the nose, thesection of said lower base body increasing in the direction of the tipof the tooth until defining a maximum gap corresponding with the maximumheight of the lower base body, and the upper and lower surfaces of theappendage progressively separate from one another from a point close toor at the free end of the nose, the section of said appendage increasingin the direction of the tip of the tooth until determining a maximum gapdefining the maximum height of the appendage, such that the union of themaximum heights of the lower base body and of the appendage determine aline of maximum height of the nose of the tooth, such that after saidline of maximum height of the nose of the tooth, the upper surface ofthe appendage and the lower surface of the lower base body begin toconverge towards the tip of the tooth until the union of both surfacesat a union line, the union line of both surfaces being located on theside of the wear part of the tooth and in front of the line of maximumheight of the nose of the tooth.
 2. A tooth according to claim 1,wherein the upper and lower surfaces of the lower base body of the noseprogressively separate from one another from the free end of the nose.3. A tooth according to claim 1, wherein the upper and lower surfaces ofthe appendage progressively separate from one another from the free endof the nose.
 4. A tooth according to claim 1, comprising a collar orflange located in a perimeter of the tooth and coinciding with the gapbetween said front wear part of the tooth or tip and said rear part ornose.
 5. A tooth according to claim 4, wherein the collar has a variablethickness or width in different areas of a perimeter of the collar.
 6. Atooth according to claim 5, wherein the thickness of the collar isgreater in upper and lower areas of the collar to resist stresses whencontact is made between these areas of greater thickness and theadaptor.
 7. A tooth according to claim 4, wherein the collar has aconstant thickness or width.
 8. A tooth according to claim 1, whereinthe nose of the tooth is hollow to reduce the weight of the tooth.
 9. Atooth according to claim 1, wherein the nose has a vertical housing forhousing a vertical pin for retaining the tooth with the adaptor.
 10. Atooth according to claim 9, wherein said pin does not require the use ofblows with a mallet or hammer for inserting the pin in or removing thepin from the housing.
 11. A tooth according to claim 1, wherein thelower base of the appendage is larger than the upper base of theappendage.
 12. The tooth according to claim 1, wherein the tooth isconfigured for use with an adaptor configured to attach the tooth to apropeller of a dredging machine.
 13. An adaptor for being coupled with atooth, having a coupling at one end and at an end opposite to that ofthe coupling a housing for receiving a rear projecting part or nose ofthe tooth, which is completely inserted in said housing, said housingbeing formed by: a lower base hollow with a section of at least foursides with rounded vertices, an upper surface and a lower surface, ahollow upper appendage, with an upper surface and a lower surface,arranged on the lower base hollow and connected thereto, forming thehousing of the nose of the tooth, and a trapezoidal section the upperand lower bases of which are respectively determined by the upper andlower surfaces of the housing, the lower base being narrower than theupper surface of the lower base hollow and said hollow appendage beingcentered with respect to the upper surface of the lower base body, anopening at an end opposite to the end for coupling to the blade, and abottom of the hollow, located at the end opposite to that of the openingand close to the coupling to the blade, wherein the upper and lowersurfaces of the lower base hollow progressively separate from oneanother from a point close to the bottom of the hollow of the adaptor,the section of said base hollow increasing in the direction of theopening of the adaptor until defining a maximum gap corresponding with amaximum height of the lower base hollow, and the upper and lowersurfaces of the hollow upper appendage progressively separate from oneanother from a point close to the bottom of the hollow of the adaptor,the section of said hollow appendage increasing in the direction of theopening of the adaptor until determining a maximum gap defining amaximum height of the hollow appendage, such that the union of themaximum heights of the lower base hollow and of the hollow appendagedetermine a line of maximum height of the opening of the housing of theadaptor, such that from said line of maximum height the upper surface ofthe hollow appendage and the lower surface of the lower base hollowingbegin to converge in the direction opposite to that of the bottom of thehollowing until the union of both surfaces form a union line located onan opposite side of the bottom of the hollow and in front of the line ofmaximum height of the opening of the hollow of the adaptor.
 14. Anadaptor according to claim 13, comprising at least one groove in acontact area of the adaptor with the tooth for inserting a tool andaiding in removing the tooth.
 15. An adaptor according to claim 13,wherein the adaptor has a vertical housing for housing a vertical pinuseful for retaining the tooth with the adaptor.
 16. An adaptoraccording to claim 13, wherein said pin does not require the use ofblows with a mallet or hammer for inserting the pint in or removing theping from the housing.
 17. An adaptor according to claim 13, wherein thelower base of the hollow appendage is larger than the upper basethereof.
 18. An adaptor according to claim 13, wherein the outer contourof the hollow has the same section as that of the hollow.
 19. Theadaptor according to claim 13, configured to be attached to a blade of acutter head of a dredging machine.
 20. A tooth and adaptor assembly forbeing connected to a dredge, comprising: a tooth having a front wearpart or tip intended for being in contact with dirt and stones, and arear coupling part, wherein said rear coupling part is a projection ornose has comprising: a lower base body, with a section of at least foursides with rounded vertices and with an upper surface and a lowersurface, an upper appendage arranged on the lower base body, with anupper surface and a lower surface forming an upper base and a lower baseof a trapezoidal section, respectively, the lower base being narrowerthan the upper surface of the lower base body and being centered withrespect to the upper surface of the lower base body, a free end oppositeto the front wear part or tip, and an end opposite to the free end andattached to the tip of the tooth, wherein the upper and lower surfacesof the lower base body progressively separate from one another from apoint close to or at the free end of the nose, the section of said lowerbase body increasing in the direction of the tip of the tooth untildefining a maximum gap corresponding with the maximum height of thelower base body, and the upper and lower surfaces of the appendageprogressively separate from one another from a point close to or at thefree end of the nose, the section of said appendage increasing in thedirection of the tip of the tooth until determining a maximum gapdefining the maximum height of the appendage, such that the union of themaximum heights of the lower base body and of the appendage determine aline of maximum height of the nose of the tooth, such that after saidline of maximum height of the nose of the tooth, the upper surface ofthe appendage and the lower surface of the lower base body begin toconverge towards the tip of the tooth until the union of both surfacesat a union line, the union line of both surfaces being located on theside of the wear part of the tooth and in front of the line of maximumheight of the nose and the tooth; an adaptor for being coupled with thetooth, having a coupling at one end and at an end opposite to that ofthe coupling a housing for receiving a rear projecting part or nose ofthe tooth, which is completely inserted in said housing, said housingbeing formed by: a lower base hollow with a section of at least foursides with rounded vertices, an upper surface and a lower surface, ahollow upper appendage, with an upper surface and a lower surface,arranged on the lower base hollow and connected thereto, forming thehousing of the nose of the tooth, and a trapezoidal section the upperand lower bases of which are respectively determined by the upper andlower surfaces of the housing, the lower base being narrower than theupper surface of the lower base hollow and said hollow appendage beingcentered with respect to the upper surface of the lower base body, anopening at an end opposite to the end for coupling to the blade, and abottom of the hollow located at the end opposite to that of the openingand close to the coupling to the blade, wherein the upper and lowersurfaces of the lower base hollow progressively separate from oneanother from a point close to the bottom of the hollowing of theadaptor, the section of said base hollow increasing in the direction ofthe opening of the adaptor until defining a maximum gap correspondingwith the maximum height of the lower base hollowing, and the upper andlower surfaces of the hollow upper appendage progressively separate fromone another from a point close to the bottom of the hollow of theadaptor, the section of said hollow appendage increasing in thedirection of the opening of the adaptor until determining a maximum gapdefining a maximum height of the hollow appendage, such that the unionof the maximum heights of the lower base hollow and of the hollowappendage determine a line of maximum height of the opening of thehousing of the adaptor, such that from said line of maximum height theupper surface of the hollow appendage and the lower surface of the lowerbase hollow begin to converge in the direction opposite to that of thebottom of the hollowing until the union of both surfaces form a unionline located on the opposite side of the bottom of the hollow and infront of the line of maximum height of the opening of the hollowing ofthe adaptor; and a retaining system securing the fastening of the toothin the adaptor.
 21. A tooth configured to be connected to an adaptor,comprising: a front wear part configured to contact dirt and stones; arear coupling part in the form of a projection or nose; the rearcoupling part comprising: a lower base body comprising an upper surfaceand a lower surface; an upper appendage arranged on the lower base body,the upper appendage comprising an upper surface and a lower surfaceforming an upper base and lower base of a quadrilateral section,respectively; a free end opposite to the front wear part; and an endopposite to the free end and attached to the front wear part; the upperand lower surfaces of the lower base body progressively separate fromone another from a point close to or at the free end of the nose, thesection of lower base body increasing in the direction of the front wearpart of the tooth until defining a maximum separation between the upperand lower surfaces of the lower base body; the upper and lower surfacesof the upper appendage progressively separate from one another from apoint close to or at the free end of the nose, the section of said upperappendage increasing in the direction of the tip of the tooth untildefining a maximum separation between the upper and lower surfaces ofthe upper appendage; the union of the maximum separation of the lowerbase body and the maximum separation of the upper appendage join todefine a line of maximum height of the nose of the tooth, such thatafter the line of maximum height of the nose of the tooth in a directiontoward the front wear part, the upper surface of the upper appendage andthe lower surface of the lower base body begin to converge towards thetip of the tooth.
 22. The tooth according to claim 21, wherein thequadrilateral section is trapezoidal.
 23. The tooth according to claim21, wherein the quadrilateral section extends up to a beginning of thefront wear part.
 24. The tooth according to claim 21, wherein the uppersurface and the lower surface of the upper appendage form an upper baseand lower base of the quadrilateral section, respectively, the upperbase and the lower base narrower than the upper surface of the lowerbase body along an entire length of the upper appendage where theappendage overlays the lower base body.
 25. The tooth according to claim21, wherein the upper appendage is centered with respect to the uppersurface of the lower base body.
 26. The tooth according to claim 21,wherein the tooth is a dredging tooth.